4Department Of Surgery, The Chinese University of Hong Kong, Hong Kong/CN

5St. James's University Hospital, Leeds/GB

6Sun Yat-Sen Cancer Center, Taipei/TW

7Rigshospitalet, Copenhagen University Hospital, Copenhagen/DK

Abstract

Background

Based on SEER database and a Chinese multicenter registry, we previously identified a benchmark for indicating sufficient lymph node (LN) examination among node negative NSCLC patients (Liang et al. J Clin Oncol 2016). Due to variability of LN examination practice, some patients with less than 16 examined LNs might be understaged and therefore have worse survival outcome. This benchmark agrees with the reported mean LN being harvested during complete pulmonary and mediastinal LN exploration, which could serve as a sign for adequate systematic LN sampling and theorectically be applicable to node positive patients as well. We sought to determine its prognostic value among node positive patients using SEER database.

Methods

The United States Surveillance, Epidemiology, and End Results (SEER) database on stage I to IIIA completely resected NSCLC (1990-2010) were extracted. Patients were dichotomized according to examined LN count (<16 vs. > =16). Multivariate Cox regression model was used to compare the overall survival (OS) and cancer specific survival (CSS) between groups under adjustment for other prognostic factor.

Results

A total of 12,407 cases met the inclusion criteria with complete data were studied. The median followup was 7.6 years (range 0.1 to 10.0). Patients with <16 examined LNs remained a significant unfavorable factor in terms of both OS (HR 1.34, 95% CI 1.27 to 1.43, P

Conclusions

This study confirmed that 16 exmamined LNs could also be considered a benchmark for systematic LN examination among node positive NSCLC patients despite the number of positive LNs. Node positive NSCLC with less than 16 LNs being harvested should be cautiously evaluated for the quality of LN examination and indication for subsequent treatment.